Differential usage of two in-frame translational start codons regulates subcellular localization of<i>Arabidopsis thaliana</i>THI1

Chabregas, Sabrina Moutinho; Luche, Douglas D.; Sluys, Marie‐Anne Van; Menck, Carlos Frederico Martins; Silva-Filho, Márcio C.

doi:10.1242/jcs.00228

Cited by 71 publications

(50 citation statements)

References 40 publications

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“…The shorter isoform may be targeted to mitochondria, while the longer isoform tends to be targeted to the plastid. The alternative upstream initiation site can even take the form of a non-AUG start codon, or it may be an AUG in a weak context (Kobayashi et al, 2001;Kobayashi et al, 2002;Chabregas et al, 2003;Silva-Filho, 2003;Christensen et al, 2005;Wamboldt et al, 2009). Two related cases deserve special attention.…”

Section: Alternative Translation Initiation Sitesmentioning

confidence: 99%

Translational Regulation of Cytoplasmic mRNAs

Roy

Arnim

2013

The Arabidopsis Book

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Translation of the coding potential of a messenger RNA into a protein molecule is a fundamental process in all living cells and consumes a large fraction of metabolites and energy resources in growing cells. Moreover, translation has emerged as an important control point in the regulation of gene expression. At the level of gene regulation, translational control is utilized to support the specific life histories of plants, in particular their responses to the abiotic environment and to metabolites. This review summarizes the diversity of translational control mechanisms in the plant cytoplasm, focusing on specific cases where mechanisms of translational control have evolved to complement or eclipse other levels of gene regulation. We begin by introducing essential features of the translation apparatus. We summarize early evidence for translational control from the pre-Arabidopsis era. Next, we review evidence for translation control in response to stress, to metabolites, and in development. The following section emphasizes RNA sequence elements and biochemical processes that regulate translation. We close with a chapter on the role of signaling pathways that impinge on translation.

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Section: Alternative Translation Initiation Sitesmentioning

confidence: 99%

Translational Regulation of Cytoplasmic mRNAs

Roy

Arnim

2013

The Arabidopsis Book

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“…Arabidopsis THI1 localizes to the mitochondria and chloroplasts (Chabregas et al, 2003). Previously, Belanger et al (1995) used a THI1 antibody to show that the maize THI1 protein localizes to plastids.…”

Section: Thi2 Is a Plastid-localized Proteinmentioning

confidence: 99%

A Maize Thiamine Auxotroph Is Defective in Shoot Meristem Maintenance

et al. 2010

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Plant shoots undergo organogenesis throughout their life cycle via the perpetuation of stem cell pools called shoot apical meristems (SAMs). SAM maintenance requires the coordinated equilibrium between stem cell division and differentiation and is regulated by integrated networks of gene expression, hormonal signaling, and metabolite sensing. Here, we show that the maize (Zea mays) mutant bladekiller1-R (blk1-R) is defective in leaf blade development and meristem maintenance and exhibits a progressive reduction in SAM size that results in premature shoot abortion. Molecular markers for stem cell maintenance and organ initiation reveal that both of these meristematic functions are progressively compromised in blk1-R mutants, especially in the inflorescence and floral meristems. Positional cloning of blk1-R identified a predicted missense mutation in a highly conserved amino acid encoded by thiamine biosynthesis2 (thi2). Consistent with chromosome dosage studies suggesting that blk1-R is a null mutation, biochemical analyses confirm that the wild-type THI2 enzyme copurifies with a thiazole precursor to thiamine, whereas the mutant enzyme does not. Heterologous expression studies confirm that THI2 is targeted to chloroplasts. All blk1-R mutant phenotypes are rescued by exogenous thiamine supplementation, suggesting that blk1-R is a thiamine auxotroph. These results provide insight into the role of metabolic cofactors, such as thiamine, during the proliferation of stem and initial cell populations.

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“…Further characterization showed that THI1 has two functions: it is involved in the thiazole synthesis of the thiamine biosynthesis pathway and in DNA repair [28,29]. Also, THI1 possesses a signal peptide at its N terminus, which targets the THI1 protein to mitochondria and chloroplasts [31,32]. The second is the Arabidopsis thaliana HMPPK/TMPPase gene (At1g22940) [30,33].…”

Section: Introductionmentioning

confidence: 99%

AtTHIC, a gene involved in thiamine biosynthesis in Arabidopsis thaliana

Kong

Zhu

et al. 2008

Cell Res

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Thiamine (vitamin B1) is an essential compound for organisms. It contains a pyrimidine ring structure and a thiazole ring structure. These two moieties of thiamine are synthesized independently and then coupled together. Here we report the molecular characterization of AtTHIC, which is involved in thiamine biosynthesis in Arabidopsis. AtTHIC is similar to Escherichia coli ThiC, which is involved in pyrimidine biosynthesis in prokaryotes. Heterologous expression of AtTHIC could functionally complement the thiC knock-out mutant of E. coli. Downregulation of AtTHIC expression by T-DNA insertion at its promoter region resulted in a drastic reduction of thiamine content in plants and the knock-down mutant thic1 showed albino (white leaves) and lethal phenotypes under the normal culture conditions. The thic1 mutant could be rescued by supplementation of thiamine and its defect functions could be complemented by expression of AtTHIC cDNA. Transient expression analysis revealed that the AtTHIC protein targets plastids and chloroplasts. AtTHIC was strongly expressed in leaves, flowers and siliques and the transcription of AtTHIC was downregulated by extrinsic thiamine. In conclusion, AtTHIC is a gene involved in pyrimidine synthesis in the thiamine biosynthesis pathway of Arabidopsis, and our results provide some new clues for elucidating the pathway of thiamine biosynthesis in plants.

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Differential usage of two in-frame translational start codons regulates subcellular localization ofArabidopsis thalianaTHI1

Cited by 71 publications

References 40 publications

Translational Regulation of Cytoplasmic mRNAs

Translational Regulation of Cytoplasmic mRNAs

A Maize Thiamine Auxotroph Is Defective in Shoot Meristem Maintenance

AtTHIC, a gene involved in thiamine biosynthesis in Arabidopsis thaliana

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